In the field of dry slide diagnostic analysis, it has been most common, particularly in the large analyzers, to package the slide test elements in a cartridge. Such cartridges keep the essentially identical members of a particular lot of an assay together, and allow the analyzer to properly interface with the slide elements. These features are illustrated in, e.g., U.S. Pat. Nos. 4,187,077 and 4,190,420.
Notwithstanding the outstanding success of such packaging, as witnessed by the hundreds of thousands of cartridges that have been sold in the 80's by Eastman Kodak Co. under the trademark "Ektachem", there remains some drawbacks in such use of cartridges. That is, the cartridges are a sizable contribution to the expense of the slide elements, and further require a careful determination of when they are empty, as is explained in the aforesaid '420 patent. Still further, even after determining that they are empty, the empties have to be disposed of--a sizable problem as throughput is increased. Because of these drawbacks, there has been interest in packaging an assembly of slide elements without requiring the use of a cartridge. However, due to the fact that the readily apparent solutions lack a sturdy way of keeping together the identical, lot-specific members of the stack, sans cartridge, there has not been an acceptable way of eliminating the cartridge prior to this invention.
Yet another drawback of cartridge-supplied slide elements has been the manner in which coded information is supplied to identify the assay of the cartridge, e.g., by bar codes. Either the cartridges are printed directly, or printed labels have been used heretofore. Such labels require a separate printing operation and then a correct combining of the printed label with its associated cartridge. It would be more advantageous to inherently provide the coding, e.g., a bar code, simply by the act of assembling together the stack of slide elements.